Note: The use of RECOVER DATABASE UNTIL TIME <time> SNAPSHOT TIME <time> falls under "Storage Snapshot Optimization" feature which requires the Oracle Advanced Compression option license to use. (Applicable starting Oracle 12c).
1) If you do not want to recover the cloned database beyond a snapshot time, you do not need to use SNAPSHOT TIME and need not place the database in hot backup mode.
2) If you want to recover the cloned database to a point in time after the snapshot time and do not have "Oracle Advanced Compression" license, you should place the source database in hot backup mode prior to taking snapshots.
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